Off-peak water heating system



3 Sheets-Sheet l C. M. OSTERHELD Filed Oct. l2, 1940 OFF-PEAK WATER HEATING SYSTEM und 5 Sheets-Sheet 2 C. M, GSTERHELD Filed Oct. 12, 1940 d ad GFF-PEAK WATER HEATING SYSTEM f Qu 2 Dec. 16, 1941.

DC- 16, 1941- c. M. osTERHELD OFF-PEAK WATER HEATING SYSTEM Filed Oct. l2, 1940 I5 Sheets-Sheet 3 xNvENToR CLARK/ 03m-Ryan Bv Eff-5 ATTORNEY Patented Dec. 16, 1941 l 2,266,245 A Y. oFF-PEAK WATER HEATING SYSTEM Clark M. Osterheld, Stoughton, Wis., assignor to. McGrawl Electric Company, Elgin, Ill., a corporation of Delaware Application October 12, 1940, Serial No. 360,877

NT OF-FICE io claims. |(ci. 21Min' My invention relates to water heating systems and more particularly to off-peak water heating systems.

One of the objects of my invention is to provide arelatively simple system which will cause energization of the heater of a hot water tank at the start of an off-peak period under certain conditions and which will delay energization of the heater under certain other conditions, referwater thus withdrawn being an appreciable quantity.

Other objects of my invention will either be apparent from a description .of several forms of systems embodying my. invention or will be pointed out hereinafter and particularly set forth in the appended'claims.

In the drawings,

Figure 1 is a diagrammatic representation of ring more particularlyto the quantity oi' hot 10 a water-fheatingsystem embodying my invenwater in the tank at the start of an oif-peak tion as applied-to a domestic hot water tank, the period. latter` being shown in vertical section, Another object of my invention is to provide Fig. 2 is a View similar to Fig. 1 but showing a plurality of means controlled separately and a slightlydiil'erent form of system, jointly in accordance with time and with the Fig. 3 is a view, in front. elevation, of a part temperature of a predetermined part of the of a timing means and switches controlled therewater in a hot water tank to cause energization by constituting a part of my improved water of the heater at the start of an off-peak period heating system, the parts of the timer being or to delay such energization for a predetershown in a somewhat different position than mined adjustable part of an olf-peak period. that in which they are shown inFig. 2 of the Another object of my invention is to provide drawings a time and temperature controlled vmeans for Fig. 4 is a view of a still further modiilcation causing selective energization of the heater of of off-peak water heating system embodying my a hot water tank at a time changingin accordinvention, and, e ance with the amount of cold water in the tank Fig. 5 is a view similar to Fig. 3 showing cer' at the start of an ofi-peak period and for protain parts of my system ina di'erent position viding thermally controlled means responsive than that in which they are shown in Fig. 4 of to the temperature of the water in a predeterthe drawings. mined part of the tank to cause prolongation of Referring first of all to Fig. 1 of the drawings, the energization of the heater beyond the end I have there illustrated a continuously operative of an oil-peak period in accordance with the timing means Il including, for purposes of ily' quantity of cold water in the tank at the end of lustration, a synchronous electric motor i3 conan oil-peak period. i nected to supply circuit conductors l5 and I'l Another object of my invention is to provide so that the motor will operate during al1 of the an oli-peak water heating system in'which pro- 35 time that energy is supplied to the conductors longation of the energization of the heater of a I5 and ll. A worm gear I9 is mounted on the hot water tank is effected when the tank is motor shaft and engages a worm wheel 2l which either not substantially full of hot water at the latter is mounted on a shaft 23. A cam disc 25 end of an off-peak period or a predetermined is also mounted on shaft 23 and the greater part fractional part of the water content of the tank 40 of the periphery of disc 25 has a certain outer is not hot at the end of an off-peak period. radius while a portion 2l, namely the off-peak Another object of 4my invention is to provide portion, has a greater outer radius. It will be an off-peak water heating system in which enernoted that the peripheral extent of the portion gization of the electric heater of a hot water 2l of greater radius, is substantially one-third tank is delayed for an adjustably predetermined Of the total periphery of cam disc 25 which latlength of time after the start of an off-peak ter is rotated through one complete turn in a period under certain conditions connected with day of twenty-four hours. The time-extent of the quantity of ho't water in the tank at predeportion 2l is therefore substantially eight hours termned times, which system will lcause dewhich, for purposes of illustration, has been energization of the electric heater in case all of assumed to be the length of an oil-peak period the water in the tank is hot during the rest of desired by the central station of the utility supan off-peak period after the delay period and in plying current to the conductors l5 and il. It which reenergization of the heater is effected in may further be assumed for illustrative purposes, case withdrawal of hot water occurs during the r that the position of cam disc 25 is that which rest of the oli-peak period, the amount of hot "5 will be occupied by it at 10:00 p. m. so that the oft-peak period of eight hours will end at approximately 6 a. m. It is to be understood, however, that, within the scope of my invention, I

lmay make the peripheral extent of portion 21 more or less than that shown in Fig. 1 of the drawings and that disc 25 may be positioned on shaft 23 at some other position relatively to the shaft so that it is possible to .vary not only the durationl of an off-peak period but also the starting and the ending time thereof. I desire to p'oint out also that while I have shown a specific embodiment, in a simple form of a continuously operative timer, I donot'desire to belimited thereto but I may use any other timer effective for the same general purpose since the continuously operative timing means constitutes" no fundamental part of my invention.

The water heating system to be presently described in detail is adapted to be operatively associated with a hot water tank and for illustrative purposes I have shown the usual kind of circular elongated hot water tank 29 used for domestic purposes. A cold water inlet pipe 3| is provided at the vbottomof the tank-anda hot water outlet '.pipe 3 3is provided at thetop-,of the tankwhich latter may be surrounded by a mass of suitable heat insulating material which is held in proper operative position by an outer casing 31, all in a manner now well known inthe art.

I provide an electric heating element 39 which, again for'illustrative purposes, I have indicatedy as extending peripherally around the tank 29, and located inraftunnel 4|. Reference may here vbe made to my copending application Ser. No.

284,88l'led July 1'1, ,19.39, in which I have disclosed and claimed anrelectric heaterlwhich I may use with the present water heating system.

T o control the energization of heater l39 I provide a main timer `controlled switch 43 which in-.

cludes a relatively rigid contact arm 45 and a rel' silientl contact arm 41 which latter is normally biased out of engagement with-contact arm 45 but is adapted to be moved. into engagementY therewith by the cam portion 21 engaging a lug 49 mounted on the arm i1.A Supply circuit con ductor I5 is connected to Contact arm 41 by a conductor 5| and contact arm 45 is connected through a conductor 53 with one of a pair of xed contact members 55 of an electromagnet switch or contactor 51 which includes in addition to the 1 xedcontact members 55, a magnetizable core member'59, a coill and a contact bridging member 63. It is to be noted that when coil 8| is traversed by an electric current, core member 59: will, bepenergize'd and moved to substantially the position shown in Fig. l of the drawings, whereby Contact bridging member 63 will be out 0f en-v gagement with contact members 55, but that when .coil 8| is deenergized, contact bridging vmember 63 will drop downwardly into engagemember 1| suitably secured to the wall of tank29 to extend through the wall into the tank to be engaged by the water in the tank at a lower por'- tion thereof. The switch includes also an expan-` sion rod 13 engageable with resilient contact arm 61 to cause it to move out of engagement with a 7.',

relatively rigid contact arm 15, this disengagement occurring when the water surrounding tubular member 1| has been heated to a certain relatively high temperature, generally denominated by the term Hot I desire it t0 be understood that any other form of thermally actuable switch effective for the same purpose may be used by me and I have shown a simple form .of ther mally actuableswitch vin order to illustrate the desired method of operation of that part of my system.

I provide an auxiliary timer actuated switch 11 which includes-'an outer' relatively rigid Contact arm19, an inner resilient contact arm 8| which has a lug .83 of ,electric insulating material thereon which lug i's'adapted to be engaged by a portion of `a camdisc 81, the portion 85 having a larger outer radius than the rest of the cam disc 81. The cam disc 81 is adjustably mounted on shaft 23 and may be mounted thereon adjacent to cam disc 25 to permit of using a stud or screw 89 extending through an elongated arcuate slot 9| in disc 81 to fix the position of cam disc 81, and particularly of the portion 85 thereof, relatively to vthe position of theportion 21 of cam disc 25. Itv will `De noted that auxiliary. switchl 11 is in closed position at substantially the same time that switch 43 has been ,moved into closed position, that is, at 10:00 p. m.

Contact arm 45 isy connected through a conductorY 93 with contact arm 19 and. contact erm 8| is connected through a conductor 95 with one terminal of coil 8|, the other terminal-of which is connected through a conductor 91 with a relatively rigid contact arm 99 of an auxiliary or upper thermally actuable switch 10|. This switch |0| includes also a tubular member |03 similar to tubular member 1|, an expansion rod |05 and a resilient contact arm |01 normally biased out of engagement with contact arm 99 but adapted to be moved into engagement therewith by expansion rod |05 when tubular member |03 is sur rounded by hot water.. Contact arm |01 is connected through a conductor |09 with contact arm .61- of vthe main thermally actuable switch 89 Contact arm 15 of main thermal switch 89 is con nected through a conductor II| with the other supply circuit conductor i1.

The main timer controlled switch 43, the auxiliary timer controlled. switch 11, the electromagnetic contactor 51, the auxiliary thermal switch I0! and the main thermal switch 59 cooperate, under certain operating conditions to be hereinafter more clearly set forth, to determine the .timeof energization of the heater 39 during an ofi-peak. period,vsuch energization being adapted to be eiiected at either the start of an offpeak period or after an adjustably predetermined delay.

I provide furtherv thermally-controlled means for causing prolongation of the energization of the heater 39 under certain operating conditions, this means including a -second electromagnetic contacter |3including a coil l l5, a magnetizable armature core ||1, a contact bridging member ||9 connected with the core and adapted to enl gage with and be disengaged from a pair of fixed contact members |2|. One terminal of coil ||5 is electrically connected to one of the contact members |2| and also, through a conductor |23, with conductor 65. The other terminal of coil H5 is connected through a conductor |25 with conductor |09. y

It is, of course evident that should the tank 29'be completely filled with hot water at the start 2,266,245 of the off-peak period, the main thermal switch S9 wouldv be in open position and no kenergization of the heater 39 would occur since its energizing circuit would have been interrupted by disengagement of contact arms 61 and 15. Let it be assumed, however, that the tank contains an appreciable amount of cold water which,in tanks of this general type, will be located in the lower part of the tank and since I prefer to locate the main thermal switch 69 in such a position that it will be moved to open position only when the tank is substantially full of hot water, this switch will be closed. 4

If it be further assumed that the tank is at least one-half full of hot Water so that auxiliary thermal switch l| is in closed position, no energization of heater 39 can be effected since'coil 6| of the rst named electromagnetic contactor,

which may be designated as the delay contactor,

will be energized through a circuit extending substantially as follows: From supply circuit conductor I through conductor 5|, contact arms 41 and 45 which are in engagement -at this time, through conductor 93,'through engaged contact arms 19 and 8| which are also in engagement with each other at this time, through yconductor 95, coil 6|, conductor 91, through Contact arms 99 and |01 which are in engagement with each other, through conductor |09, through contact arms 61 and 15 which are in engagement with each other and through conductor to the other supply circuit Vconductor |1. This'holds contact bridging member 83 out of engagement with xed contact members 55 and it is thus evident that, under these assumed operating conditions, more particularly that while there is an appreciable quantity of cold water in the tank, substantially more than half of its water content is hot.

Let it be assumed that a slightly different condition exists as to the quantity of hotwater in the tank, namely that the tank is less than onehalf fully of hot water so that tubular-member |03 is surrounded by cold water, that is, the'tank is appreciably less than one-half full of hot water. In this case the hereinbefore describedl energizing circuit through coil 6| of the delay contactor will not be provided upon closure of timer controlled switches 43 and 11, it being evident, of course, that if the upper thermal switch |0| is subject to cold water. the lower main thermal switch 69 will also be subject to cold water.

The delay period is shown approximately or substantially, in Fig. 1 of the drawings, as extending for about twohours and at the end of that time the contact arm 8| will be permitted to move out of engagement with contact arm 19 when lug 83 on arm 8| moves oli the portion 85 of disc 81, it being 'understood that discs 2|, 25 and 81 are rotated continuously in a clockwise A direction as indicated by the arrow on disc 25.

In case the hereinbefore described energizing circuit through coil 6| of the delay contactor was energized, as hereinbefore dcribed, this energization will be interrupted when timer-controlled switch 11 is moved into open position at the end of a delay period'with resultantdownward movement of core 59 and contact bridging member 63, the latter then engaging the fixed contact members 55. This closes an energizing circuit through heater substantially as Iollows: From supply circuit conductor I5, through conductor 5|, contact arms 45 and 41, conductor 53, cooperating engaged contact members 55 and B3, conductor 65, heater 39, engaged contact arms 81 and 15 and through conductor I|| to the other supply circuit conductor |1.

At the time ot closure of the energizing circuit for the heater through main timer controlled switch 43 and through the contact members of delay contactor 51, it being noted that all of these switches are in series circuit relation relatively to each other and to the main thermal switch 69, an energizingl circuit through coil I |5 of prolongation contactor ||3 is closed, extending substantially as follows: From supply circuit conductor I5 through'conductor 5|, engaged contact arms 41 and 45, conductor 53, engaged Contact members 55 and 63, conductor |23, coil ||5, conductor |25, conductor |09, through contact arms 81 and 15 and then through conductor to the other supply circuit conductor |1. It was hereinbefore stated that one of the fixed contact members |2| was connected to conductor 65 by conductor |23 and it will be noted that this connects one of the fixed contact members |2| to one of thexed contact members 55 of the delay contactor 51. The other fixed contact member |2| is connected by a conductor |21 with conductor 5|. Upon energization of the coil |5'of the prolongation contactor ||3, core member ||1 and contact bridging member I9 are moved upwardly, whereby the'series connectedl switches 43 and 51 are shunted by the cooperating contact members of contactor ||3, this shunt circuit being traced generally as extending through conductor |21, the' cooperating contact membersv||9 and I2| and conductor |23. It is to be assumed that the tank is more than one-half full of hot Water toward the end of an olf-peak period and while it may happen that the tank is completely filled with hot water before the end of the off-peak period, it is assumed for purposes of describing the operation of the prolongation contact H3, that the tank still contains as appreciable amount offcold Water at the end of the off-peak period, In this case the contactor |3 will remain in the position shown by broken lines in Fig. 1 of the drawings, a holding circuit for the I,coil V||5 being provided extending substantially as follows: From supply circuit conductor |5 through conductors 5`| and |21, through the engaged contact members |2| and H9, through coil ||5, through conductors |25 and |09, through the contact arms 61 and 15 and from there through conductor to the other supply circuit conductor |1 and it may be pointed out that -this holding circuit is independent of the main timer controlled switch 43 so that energization of this holding circuit will continue after or beyond the end ofvan off-peak period whereby an energizing circuit for the heater 39 m provided, extending substantially as follows: From supply circuit conductor |5 through conductors 5| and |21, through engaged contact members |2| and H9, through conductor |23 and $5, through heat,-

- er 39,'. through the engaged contact arms 61 and -sary to cause this action is, of course, variable 15 and then through conductor to the other supply circuit conductor |1,

The amount of cold water in the tank necesand may be only suiicient to cause the main thermal switch 69 to be closed o1' the cold water may extend well thereabove to the auxiliary thermal switch |0|. It is thus evident that the amount of overrun or prolongation of the energiza'tion of the heater 39 will be variable depending upon the presence of at least an appreciable amount of cold water in the tank and increasing generally with the amount of cold there shown a water heating system .substantial-v 1y similar in layout and connection and in operation Yto that shown in Fig. 1 of the drawings, the main difference between these two systems being that whereas the coil ||5 of the prolongation contacter ||3 is a shunt coil, the coil of the prolongation contacter provided in the system of Fig. 2 is a series coil. I have, therefore, applied `the numerals of Fig. 1 of the drawings wherever they can properly be applied to corresponding elements in Fig. 2 of the drawings either identical or operating in the same manner as in Fig. 1

of the drawings. Y

I provide a lower main thermally actuable switch E9 and an upper auxiliary thermally actuable switch IUI in this system and I provide a' prolongation electromagnetic contactar |29 comprising in addition to a coil |3| which is adapted to carry aire latively heavy current, a magnetizable armature core |33 having connected therewith a contact bridging member `|35 which is adapted to engage with and be disengaged from a pair of xed contact members |31. Contact arm 41 and conductor 5| are connected to one of the flxedcontact members |31 through a conductor |39, while the other fixed Contact member |31 isvconnected to one terminal of coil |3| and to contact arm 45 by a conductor |4|. The other terminal of coil |3| is connected to one of the fixed contact members 55 of contactor 51 through a conductor |43.

Contact arm I 01 of the auxiliary upper thermal switch |0| is connected through a conductor |45 with one terminal of the heater 39, the other terminal ofwhich is connected to contact arm 15. Contact'arm 51 of thermal switch ,69 is connected through a conductor |41 with the other fixed contact member 55. A conductor |49 connects-supply circuit conductor |1 with conductor It/ will be evident that vwhen the main timer controlled switch 43 is closed at the start of an |29 causes energization of the armature core |33 with resultant upward movement thereof and attendant upward movement of contact bridging member into engagement with the fixed contact members |31, but this will have no immediate effect upon the now of current throughr heater 39. It will, of course, provide a shunt circuit relative tothe main timer controlled switch 43 substantially as follows: From supply circuit conductor- I5 through conductors 5| and |39, engaged contact members |31 and |35, coil |3|, through conductor |43, through engaged contact members 55 and 63, through conductor |41,

through engaged contact arms 61 and 15/and through heater 39 and from there through conductors |45'. and |49 to the other supply circuit conductor |1. This latter energizing circuit will, as isevident, permit opening of the main timercontrolled switch 43 at the end of an off-peak Aperiod without interruption of the energization of the heater 39 in case there is still an appreciable amount of cold water in the bottom of the tank with resultant maintenance of the engagement of contact arms 61 and 15 which, as was hereinbefore stated, will remain in engagement with each other until substantially all of the water in the tank is hot. In other words, if all of the water in the tank is not hot at the end of an i ofT-peakperiod, the main thermal switch 69 will off-peak period and that if at the same time, the

auxiliary timer controlled switch 11 is also closed and if, further, the amount of cold water in the tank is sufficient to immerse tubular member |03 with consequent opening of the switch 10|, an' energizing circuit through the heater will be effected substantially as follows: From supply circuit conductor |5 through conductor 5|, contact arms 41 and 45, conductor |4|, coil |3|, conduc- A Avtor |43, cooperating engaged contact members 55 I cause of the fact that even though the contactv arms of auxiliary switch 11 are in engagement, the contact arms 99 and |01 of the auxiliary thermal switch |0| are out of engagement with each other whereby energization of the heaterv 39 is effected at the start of the off-peak period.

The ow of current, as hereinbefore described,

through coil |3| of the prolongation contacter act as a thermal prolongation means controlling the prolongation contacter |29 to continue energization of the heater until all of the water in the tank is hot.

It :may further be here pointed out that should Ait occur that all of the water in the tank has been heated to a given temperature, generally described bythe word Hot, before the end of an off-peak period with resultant deenergization of the heater, and should withdrawal of hot water occur before the end of an off-peak period, sufcient to cause immersion of the main thermal .switch 59 in cold water, the heater 39 will be reenergized and its energization would be prolonged beyond the end of an off-peak period and until substantially all of the water in the tank is hot. It is evident also that should additional withdrawals of hot water occur after the end of the off-peak period but before deenergization of the system by the main thermal switch B9, continuance of the energization of the heater 39 would be ensured, such energization continuing until substantially all of the water in the tank is hot.

Referring now to Fig. 3 of the drawings, I have there shown how it is possible in my improved water heating system to ensure start of the energzation 0f the heater at the start of an offpeak period by merely manually shifting the position of the auxiliary cam disc 81 relatively to the main` cam disc 25 in such a manner that the auxiliary timer-controlled switch `|1 will be open before the main timer switch 43 has been closed, as herelnbefore set forth. This means that it is possible for the user of a system of the kind herein described and disclosed to ensure energization of the heater beginning at the start of an off-peak period irrespective of the amount of hot water in the tank at the start of an off-peak period.

Referring now to Figs. 4 and 5 of the drawings, I have there illustrated a further modification of, more particularly, the system shown in Fig. 1 of the drawings, whereby energization of the heater 39 is delayed in case a predetermined fractional part of the Water in the tank is hot and in which case prolongation of the energization of the coil 39 is ensured in case the tankis not at least half full of hot water at the end of an oipeak period. y

I provide the `same continuously Voperative timing means as was shown in Fig. 1 of the drawings, the same delay electromagnetic switch or contactor and the same main thermalvswitch preferably located at or near the bottom of the tank. `I provide a modified form o! auxiliary thermal switch I5I comprising a tubular member |53 suitably secured to the tank 29 to close an opening in the wall of the tank in a fluidtight manner, an expansion rod I 55 in the tubular member |53, a relatively rigid inner contact arm |51, a relatively rigid outer contact arm |59 and a resilient contact arm |6| normally yieldingly biased into engagement with the inner contact arm |51 but adapted to be moved out of engagement therewith and into outer contact arm |59 by the expansion rod |55 if it and the tubular member |53 are surrounded by or responsive to hot Water. i

One end of the coil 6| of the delay contactor 51 is connected to contact arm 8| of the auxiliary timer controlled switch 11 by conductor 95 while the other end of coil 6| is connected by a conductor |63 with contact arm |59.A Contact arm |6| is connected by a conductor |65 to contact arm 15 of the main thermal switch 69, which arm is also connected to one terminal of the heater 39. Contact arm 61 is connected through a conductor |61 to the other supply circuit conductor I1.

I provide a prolongation contactor |69com prising, in addition to a coil I1I, a magnetizable core member I 13 having connected therewith a contact bridging member |15 which is adapted to be engaged with and disengaged from substantially iixed contact members |11, vall in a manner well known in the art. Contact arm 41 is connected through a conductor |19 with one of the iixed contact members |11. xed contact member |11 is connected-io one terminal oi' coil I1I, while the other terminal of coil |1I is connected through a conductor |8| with contact arm |51. The other nxed contact member |11 is connected through a conductor |83 with a conductor |85 which connects onev of the xed contact members 55 with one terminal of heater 39.

Let it be assumed that the continuously operative timer II andthe parts thereof are in the positions shown in Fig. 4 of the drawings, which, for convenience, may be assumed to beat :00 p. m. Let it be further assumed that the amount of hot water in the tank 29 is suihcient to immerse tubular member |53, that is, the tank i s more than half full of hot water. Under this condition contact arm |6| will be in the position shown in Fig. 4 and a circuit through oil 6| will be established as follows: From supply circuit conductor I5 through conductor 5|, engaged arms 41 and 45, through conductor 93 and through engaged Contact arms 19 and 8|, conductor 95, coil 6l, conductor |63, through engaged contact arms |59 and |6|, through conductor |65, through engaged contact arms and 61 and through conductor |61 to the other supply circuit conductor I1. Contact bridging member 63 will therefore be held in its raised position Where it isout of engagement with the fixed contact members 55 -and the hereinbefore traced energizingcircuit through heater 439 including more particularly the main timer controlled switch 43, the'cooperengagement-*with the The other' ating contact members 55 and 63 of the delay contractor. 51, and the main thermal switch 69 will not be provided.

At the end of a predetermined adjustable time, controlled more particularly by the auxiliary timer-controlled switch 11, this switch will be opened by reason of the fact that the portion 85 of the disc 81 will be turned out of engagement with lug 83 with resultant opening of the above described energizing circuit of coil 6| and energization of the heater 39 will then begin.

It is, of course, to be understood that in case the tank contained such an amount of cold water at the start of an oft-peak period that tubular member |53 was immersedv therein, contact arm I 6I would then be in engagement with contact the above described energizing circuit for coil 6I would not have been established and energization of the heater 39 would have .been elected at the start of the off-peak period.

In case the amount of hot water in the tank at or just before the end of an oil-peak period is not sumcient, for any reason whatever, to irnmerse the tubular member |53, the resilient contact arm |6| would then be in engagement with contact arm |51 and an energizing circuit through the coil I1 I would be established as follows: From supply circuit conductor |5 through conductor 5|, through engaged lthrough conductor 53 Y tact members 55 and ductor |85 and through conductor |83 to a con# .gaged contact arms 15 and 61 and III and |85 into the contact arms 41 and 45, and through engaged con- 63 through a part of contact member |11, through coil I1I, through con ductor |8| and through engaged contact arms |51and |6|, through conductor |65, through enfrom there to the other supply circuit I1. This would cause energization of core member |13 with attendant upward movement thereof whereby contact bridging'.4 member |15 is moved into engagement with iixed contact members 11 whereby an energizing circuit through heater 39 is established as follows:l From supply circuit conductor I5 through conductors 5| and |19, through engaged contact members |15 and |11, through conductors heater 39, from there through engaged contact arms 15 and 61 and through conductor |61 to the other supply circuit conductor I1. This circuit is not dependent upon the switch 43 which may, therefore, open at the end of an olf-peak period without aiecting continuation of the energization of the heater 39 because of the fact that a holding circuit througih coil |1I of the prolongation contacter |69 was established as follows: From supply circuit conductor I5 through conductors 5| and |19, through engaged contact members |11 and |15 through coil I1I through conductor |8| to contact arm |51 in engagement with contact arm 6|, from there through conductor and through engaged contact arms 15 and 61 to conductor |61 and from there to the other supply circuit conductor I1.

Should, therefore, the tank be less than half full of hot water at the end of the off-peak period as might happen in case of withdrawals of hot water during the oil-peak period, prolongation of the energization of the heater 39 would be ensured and it is only necessary, to ensure deenergization of the heater 39, that the amount of hot described holding circuit of coil I1 deenergization of the heater 39 and sidered asA -mayuse the term tional part of the water l Ymy invention` vcoming less than half full of and by tank water temperature for controlling said -iirst electromagnetic switch to selectively cause energization of the heater on closure of said main heater control switch by the timer at the start of an oi-peak period in case the tank is less'than approximately half full of hot water at that time, to cause anA adjustably predeter- While lfhave illustrated and described specific embodiments of thermally actuable switches responsive to'tank water temp'eratural do not desire to be limited to these particular constructionssince they have been shown mainly for illustrativel purposes and any thermally actuable switches operable in the same manner maybe used by me.

I wishto point out further that' while I have shown a specific position of the thermally actuable switches IUI and ISI as being substantially midway of the tank, my invention is not to be conbeing limited thereto even though I half-full of hot water in the specification and 'in the claims. broadly, the amount of hot water in the tank maybe expressed as being a predetermined fraccontent of a tank, which is to be understood as including all quantities less vthan the entire tank contents. I may move the auxiliary thermally actuable switch farther up in thetank or lower down in the tank as may be vdesired by a user and any generally similar position of the auxiliary thermally actuable switch is to be considered as being included in the scope of my invention. Various Vother modifications of within the scope of the appended claims are to be considered as being covered thereby.

Y heating systemffor a hot water tank having an electric heater, comprising a continuously operative timer, a main heater control switch adapted to energize s aid system and to be held'in closed position by said timer during an o-peak period, a first electromagnetic heater control switch controlled by the joint action -of time and tank water temperature controlledmeans to cause energization of the heater at the start of the off-peak period in case less than a predetermined fractional part of the water content of a tank is hot at the start of an offpeak period, to delay energization of the heater for an adjustably predetermined length of time after start of an oil-peak period in case said predetermined fractional part of the water content is hot at the start of an off-peak period and a second electromagnetic heater control switchcontrolled jointly by time and tank water temperature controlled means to prolong -energization of the heaterbeyond the end of the oi-peak period in case the tank contains less than a predetermined amount of hot water at the end of an off-peak'period. .Y

2. Anon-peak water heating system for a hot 'mined' delay in the energization of the heater in case the tank is more than approximately half full of lhot water at the start of an oir-peak perio d, a' second electromagnetic heater control switch electrically connected in shunt circuit relation 'to said main heater control switch and controlled by said means controlling said first electromagnetic switch to selectively cause deen- "ergization of the heater during the rest of an offpeak period when a predetermined part of the water in the'tank is hot, to cause prolongation of the energization of the heater beyond the end of an off-peak period in case less than said predetermined part of the water in the tank is hot and to then cause deenergization of the heater when said predetermined part of the water in the tank is hot.

3, An off-peak water heating system for a hot water tank having an electric heater, comprising Expressed peak a continuously operative timer, a main heater control switch adapted to be moved to heater energizing position by said timer at the start of an off-peak period and to be held in such position during'an ofi-peak period, means including time and tank water temperature controlled' switching means jointly cooperative with said main heater control switch to selectively cause energization of the heater at the start of an offperiod and to delay such energization of the heater for an adjustably predetermined time 'after istart of an off-peak period in accordance with the predominance of cold or hot water in the' tank at the start of an off-peak period and means including a second tank water tempera- Y ture controlled switching means to-cause prolongation of the energization of the. Vheating means beyond the end of an off-peak period in. case' the tank contains less than a predetermined quantity of hot water at the end of an off-peak period, said energization beinginterrupted when `the tank contains said predetermined quantity of hotwater.

4. An oli-peak water heating system for a hot Water tank having an electric heater, comprising water temperature controlled electromagnetic switch electrically connected in series circuit rewater tank having an electric heater, comprising a continuously operative timer, a main heater control switch adapted to be held in closed position by said timer during an oil-peak period, a first electromagnetic heater control switch electrically connected in series circuit relation to said main heater control switch, kmeans including switches controlled -separately by said timer a continuously operative timer, a main heater control switch adapted to be moved into heater energizing position by the timer at the start of i an off-'peak period and to be held in such position during an off-peak period, a thermally actuable heater control switch electrically connected in series circuit relation to said main heater control switch and adapted to be moved to heater- .deenergizing position when substantially all of the water in the tank is hot, a first time and tank lation to the main and the thermally actuable heatercontrol switches and selectively effective to cause energization of the heater on closure ofxthe main heater control switch in case the tank is less than approximately half full of hot water at the start of an OIT-peak period and to delay energization of the heater for an adjustably predetermined lengthof time in case more thanY -a predetermined fractional part of the water content of a tan'k is hot at the start of an ofi-peak period and a second tank-water-temperaturecontrolled electromagnetic switch connected in ame-a shunt circuit relation to said main heater control switch Yand said first named electromagnetic switch and eilective to cause' c'ontinuatior 1'4 'of the energization of, said heater beyondthe 'end'oi an olf-peak period inl` case thetankcontainsless than a predetermined quantity otI hot'water at the endV oi the oli-peak period -and to cause d eenergization of the heater when the'tafnk'con-- tains at least said predetermined quantityjoi' hot water. v

5. An ofi-peak water heating system for a hot '7,"An ofi-peak waterheating system for a hot water tank :havingan electric heater, comprising water tank `having an electric heater, comprising a continuouslyoperative timer, vainain *heaterA control switch adapted to bemoved intoheater energizing position by the timer at the start of an oli-peak period and to be held in such position during an'oi-peak period, 'a thermally'actuable" heater control switch electrically connected in series circuit relation to said main heater control switch and adapted to be moved toheaterdeenergizing position when substantially all oi" K the water in the tank is hot, a r'st'time and, l

tank water temperature controlled electromag netic switch electrically connected'in series cir.`

cuit relation to the main and the thermally actuable heater control switches and selectively effective to cause energization of the heater on` the heater for an adjustably predetermined length of time in case more than said. predetermined fractional part of the water content jof the't'anlrv is hot at the start of an olf-peak periodanda second electromagnetic switch connected inShlmt circuit relation to said main heater control switch f and said first named electromagnetic switch and controlled by said thermally actuable heater con-.

trol switch to cause continuation ofthe energization of the heater beyond the endo! an 01I- peak period until substantially all ofthe water in the tank is hot.

6. An off-peak water heating system for a hot water tank having an electric heater, comprisingA v a continuously operative timer, a main 'heater control switch adapted to be moved intojh'eater energizing position by the timer at the start of an ofi-peak period and to beheld in such position during an off-peak period, a thermally-actuable aA continuously-voperative timer, a: plurality of electrically connected heater4 control switches and timer and-tank water temperature responsive Ameans controlling said heater control switches to eiect energization of the heater at the start of an off-peak, period in case thetank is less than half fulloi' hot'water at the start of an ofi-peak period, to effect energization of the heater at an adjustably lpredetermined later time during the olf-.peak period in case the tank-is substantially' half full of hot water at the start of an oir-peak period to cause` deenergization of the heater when the tankis substantially full of hot water, to cause continuation o1'v the energization ot the heater beyondthe end o! an oli-peak period in case ythetank is substantially less than hal! full oi hot water. atthe en d of an oli-peak period until the. tank is substantially half tullof hot water.

8. An ofi-peak water-heating system for a hot water .tankcomprising an electric heater, a continuouslyoperativetiming means and a plurality oi 'electricallyconnected switching means oo ntrolled separately and jointlyy by the timing means and by vthe temperature of predetermined partsof the water inthe tank for causing energization of the heater at the'start of jan oilpeak period in case the tank contains more than a predetermined quantity of cold water at the start o f an oiigpeak period, for causing a delay of adjustably predetermined length of time in the `energization of the heater after the start of Aan oit-peak period in case the tank contains lessv than.. said `predetermined quantity of lcold water at the start vof an `oit-peak period, for causing energization of the heater during said delay time in case withdrawal of hot water from the'tank causes the presence of more than said predetermined quantity of cold water into the tank ,r for causingdeenergization of the heater during the., oil-peak period vwhen ysubstantially all ofthe water- -in the tank is hot and for causingcontinuation of the energizationof'the heater beyondethe end of the oli-peak period in case thetank contains more than said predetermined heater control switch electrically connectedin series circuit relation to saidmain heater control switch and adapted to be moved to heater "cle-5v quantity for com period.Y t c 9. An oil-peak waterrheating system for a hot water at the end of the oil-peak Y water tank comprising an electric heater, a continuously operative timing means, a heater con-l trol switch moved by said timing means into rand held in closed position thereby during an 0K- peak period, a thermally actuable heatercontrol switch responsive to the temperature o! the water in the lower part of the tank, an electromagnetic heater .control switch electrically connected in series circuit with said iirst and second heater control switches, a second electromagnetic `heater, control switch electrically connected in shunt circuit with said first named heater conenergization of the heater for an 'adjustably .pre-

determined length of vtime in case the tank is more than approximately half'full 'of hot water at the start of an oit-peak period and a second'V heater beyond the end of an offpeakperi0d in case less than approximately half of the water in the tank is hot at the end of an off-peakperiod trol switch and electric connection between all of said switches for causing energization oi the heater on closure of the first named heater control switch by the timing means in case of the vpresence of more than. a predetermined quantity of cold water in .the tank at vthat time, for caus- .fing a delay of an adjustably predetermined length of time in the energization of the heater in case of the presence offless than said predetermined quantity. ofl cold waterxin `the tank at ,the start-of anoiT-peak period, for causing energization of. the heater during said delay time in the in case withdrawal of hot water from thetank 'causes the tank to contain.-mo're` than saidpre- .determined quantity of cold water, for causing continuation ftheV energiza'tion of the heater beyond the lend "of the oil-peak period "in 'rcase `the tankfcontainsV more tljxan said `predeterminedquantityA of cold water at-the--end of the ofi-peak periodand for causing deenergization of=V the heate'raslsoon as snbs'tantially all of the water l' tank hasA been heated toa given temperature.J

1 0. off-peak waiterheatingV system' Afor 'a l, v, `het water'tankn comprising an'electric lheater y I and means including -aplu'rality of time .confY :f

trolled switches and a plurality of switches controlledfvbytank water temperature and by the .time-controlled switches for selectivelycausing immedatie and delayed energization of the heater 'relative to the start of an off-peak period in accordance with the quantity of hot water in the tank at that time and for selectively causing immediate deenergization of the heater at the end of an off-peak period and delayed deenergization .beyond the end of an oil-peak period in accordance with the quantity of hot water in the tankfat the end of an off-peak period.

CLARK M. OSTERHELD. 

